1. Field of the Invention
The present invention relates to a control technique of an industrial robot (hereinafter simply referred to as "robot"), more particularly, relates to a robot path planning method for determining the path of a robot, taking into consideration the bending caused by the load imposed on the robot when the robot is being controlled.
2. Description of the Related Art
In general, a load is imposed on a robot, and particularly when a heavy tool such as a welding torch is mounted, the bending of each axis of the robot owing to the load becomes too great to be neglected. With regard to bending amount which exists under the condition where calibration of the origin position of each axis of a robot (i.e., mastering) is performed (in other words, under the load condition in accordance with robot attitude or the like), it is possible, by performing mastering, to make a robot controller to take recognition of a position and an attitude of distal end of a tool (hereinafter simply referred to as "robot position") into which such bending amount is incorporated. However, since the load imposed on each axis differs depending upon a posture of the robot and a weight and shapes of the tool to be mounted, when the robot is on a general robot path, there is a discrepancy between the robot position which is recognized by the robot controller and the actual robot position. In addition, the current position data displayed on the display attached to the robot controller may no longer be accurate.
Therefore, when the robot which makes path plans at the time of programming fails to take in account of the bending caused by different loads is activated, the actual path of the robot may deviate from the desired path, even if the robot path data in the robot controller agrees with the desired path.
As of now, any robot path planning method which realizes the desired path of the robot by taking account of bending owing to the load is not known.